The biological world is an arena of nanofabrication, one that can be tapped for information about constraints on the design and production of small-scale materials. Among the most intricate of natural nanoscale materials are those that modulate light, such as the lenses, irises, and reflectors of animals (Vukusic, et al. 2003 Nature 424, p. 852). Reflective tissues are prevalent across the animal kingdom, being particularly conspicuous in species that live in the visually homogeneous pelagic environments of the ocean. In these habitats, reflectors often function in camouflaging by modulating incident sunlight or bioluminescence (Johnsen, et al. Proc. Royal Soc. London. B 2001, 269, p. 243; Johnsen, et al. Limnol. Oceanogr. 2003, 48, p. 1277). Reflectivity in animal tissues is achieved by the deposition of flat, insoluble, structural platelets of high refractive index that alternate in layers with materials of low refractive index. This arrangement creates thin-film interference, that results in reflection of some or all of the incident light (Land, et al. Prog. Biophys. Molec. Biol. 1972, 24, p. 75). In aquatic animals, reflector platelets are most often composed of purine crystals, particularly guanine and hypoxanthine (Denton, et al. Proc. Roy. Soc. Lond. A. 1971, 178, 43). In contrast, cephalopod reflector platelets do not contain these purines and studies of their biochemical and biophysical characteristics have suggested that they are composed of protein (Cooper, et al. Cell Tissue Res. 1990, 259, p. 15). However, the composition of cephalopod reflector platelets has never been definitively characterized (Cloney, et al. Amer. Zool., 1983, 23, p. 581). Each of the cited references herein are incorporated by reference in its entirety.